Effect of Low Concentration Cyanide on Startup of Expanded Granular Sludge Bed for the Treatment of Tapioca Starch Wastewater

Abstract

In this investigation, An Expanded Granular Sludge Bed (EGSB) was used to treat tapioca starch wastewater containing low concentration cyanide and the influence of cyanide concentration on the startup of EGSB reactor was conducted. On the condition of 13.4h of HRT, the chemical oxygen demand (COD) and cyanide concentration varied, The EGSB performance was assessed in terms of COD, pH, alkalinity, volatile fatty acids (VFA) and methane variation during the process. The results showed that cyanide was harmful to the anaerobic bacteria of the granular sludge in EGSB reactor for the treatment of tapioca starch waster, as the cyanide concentration was at 15mg/L, COD removal efficiency for cyanide free wastewater nearly 90%, however the efficient dropped to 80% with increasing cyanide concentration up to15mg/L; the methane production was nearly 200mg/L with cyanide concentration and dropped to a value of 2mg/L for 15 mg/L cyanide; and methanogenic activity decreased; while the influent VFA was increased, at an cyanide concentration of 0 and 5mg/L, the concentration of VFA was maintained below 100.00mg/L, but it was higher than 600mg/L in most of the cases with influent cyanide concentration of 15mg/L; SEM observation of the granules showed the predominance of Methanosaeta. sp. and the obvious damage of the bacteria located on the surface or in the inner part of some granules, leading to a deterioration of granular sludge settling velocity, and even some granules washed out.

Divergence of Granular Sludges and Microbial Communities in Two Types of Anaerobic Reactors Treating Different Wastewaters

“…Among the numerous anaerobic bioreactors, the expanded granular sludge bed (EGSB) reactor has attracted more attention in recent years due to its improved performance and economic efficiency during the anaerobic digestion of municipal wastewater [9,10]. However, unstable performance and a long startup period are still challenging problems for the EGSB reactor [11]. Accordingly, an advanced EGSB (AnaEG) reactor was developed by Zhang [12].…”

The Advanced Anaerobic Expanded Granular Sludge Bed (AnaEG) Possessed Temporally and Spatially Stable Treatment Performance and Microbial Community in Treating Starch Processing Wastewater

“…Among the different alternatives of anaerobic biotreatment, the expanded granular sludge bed (EGSB), an improved anaerobic treatment technology based on an upflow anaerobic sludge blanket (UASB), has attracted more attention in SPW treatment in recent years ( Fang et al, 2011 ; Fettig et al, 2013 ). However, its treatment performance stability is still unsatisfactory ( Zhao et al, 2012 ). Recently, an advanced anaerobic expanded granular sludge bed (AnaEG) which combines the advantages of UASB and EGSB technology was invented by Li et al (2014) .…”